Basically I’m optimizing for viral growth, otherwise the business probably isn’t worth it. I haven’t launched yet but I estimate that at 100k DAU vertical scaling/using a single instance would become a nightmare because of throughput and latency rather than data size.

I’m admittedly using a strange architecture for my use case and I realize now commenting here opened too big a can of worms as explaining exactly what I’m doing would derail the thread. Suffice it to say, my db doesn’t contain just “Bob ordered 5 widgets to Foo Lane” data.

But yes, using a more horizontal database strategy makes it very easy to manage data across realms. That’s one of the main benefits. A single DB would be much harder as far as isolation and separating test/production traffic (assuming this is what you mean by views) than having multiple separable dbs that only talk to dev/staging. And I can easily wipe out and isolate dev and staging this way. I’m frankly shocked people would advocate a single db that doesn’t allow you to do this.